So, since we are talking about SQL Server here - which is pretty darn good at using SMP, I would think the 4 core might be desirable. Again, this is going to be a mixed use box... I would say 80% straight SQL load via ODBC/OLEDB, 15% SSRS, 5% SSIS.

Despite what I've said above, I am still leaning toward the 3ghz dual core...

the SQL Server engine is capable of getting good SMP scaling
but the SQL code in your app may not
writing SQL blind to the characteristics of how the engine handle each operation does not give any certainty, in fact, for some reason, people usually chose the SQL constructs that results in poor SMP scaling

otherwise i would not have mentioned this
be carefully about applying benchmark scaling results and your application
the benchmark was tuned by the best experts in the world,
for that matter, the SQL engine itself was also built to run the benchmark
the same does not apply to your app

per what i said in my post on this matter,
i do not think i would drop from dual core 3.0GHz to quad 2.00GHz even though benchmarks show better performance for the quad at the same price
if you want to go quad, spend the extra money for the 2.66

This server is not going to have an I/O subsystem commensurate with the quad core 2.66Ghz chip...so no need to spend money on processors I won't be able to max out. I am going to stick with the dual core 3.0 Ghz.